Even with recycled content, concrete production still requires resources and energy. To minimize the amount of resources used in construction, you should find ways to use less concrete for equally solid construction.

Autoclaved cellular concrete is a type of preformed concrete block with aerated concrete. It is lighter than traditional concrete, yet it's just as strong and offers better insulation. Insulated concrete forms are another option. They are light foam blocks that hold poured concrete, then remain in the walls and foundation, reducing the amount of concrete required and, again, improving insulation.

You also can save concrete in construction by excavating a shallower foundation or using lightweight pre-cast concrete. Consult local building codes, but in most areas, a 16-inch foundation is adequate. Such a foundation can also be more energy efficient by making better use of natural subsurface insulation.